Kb18

Emulab FAQ: Using the Testbed: Are there any constraints on my topology?

Emulab FAQ: Using the Testbed: Are there any constraints on my topology?

Yes, but only those imposed by the physical hardware that is currently
available in our testbed. The constraints that people most commonly
run into are the maximum speed of our links
and the maximum number of network interface cards
(NICs) in our machines.

On the older pc600, pc850 and pc2000 machines,
you cannot get any links faster than 100Mbps,
while on the newer pc3000 and d710 machines you can get 1Gps links.
Most nodes currently have 4 experimental network
interfaces, so each node can be a member of up to 4 links or LANs.
A small number of the d710 machines have 5 interfaces.
(See the pc3000 and d710 pages for attributes
of the newer machines.)

A good strategy for making your topology fit within those limits is to
replace multiple links to a node with a LAN or with a router node.
Another approach is to use
''emulated'' network links.
Emulated links are multiplexed over the actual
physical links, up to the physical bandwidth that the physical link
can support. In other words, five 20Mb links can be multiplexed over a
100Mb physical link. More information on emulated links can be found
here. Ask Testbed Operations if you need further
assistance.